Breeding Potential of Potato Somatic Hybrids: Evaluations for Adaptability, Tuber Traits, Late Blight Resistance, Keeping Quality and Backcross (BC1) Progenies

Ten tetraploid interspecific potato somatic hybrids developed earlier through protoplast fusion between the dihaploid Solanum tuberosum L. 'C-13' and the diploid wild species Solanum pinnatisectum Dun. were used in this study. Somatic hybrids and standard control cultivars were evaluated for adaptability, tuber traits, late blight resistance and keeping quality attributes (dormancy, sprouting, weight loss and appearance after 75 days of storage) during two successive winter crop seasons (short-days) in the sub-tropical plains of India, where nearly 90% of India's potatoes are grown. Somatic hybrids showed medium to good plant vigour and late to very late plant maturity. Though none of the somatic hybrids produced equal or higher tuber yield than the control cultivars, except clone P7, all other somatic hybrids produced significantly higher marketable and total tuber yield after a 90-day growth than the parent C-13. Most of the somatic hybrids possessed higher tuber dry matter concentration, resistance to late blight and better keeping quality attributes than the control cultivars. Notably, the tubers of somatic hybrids showed a tendency for colour change from white to purple on exposure to sunlight. Breeding potential of somatic hybrids was further assessed by crossing them with commonly grown local potato cultivars for the development of backcross (BC1) progenies. In the hybridization programme, berries were formed while somatic hybrids were used either as male or female parents with common cultivars. Our results revealed that the use of bulk pollen of somatic hybrids not only resulted in higher pollination success but also helped to achieve higher numbers of true potato seeds (TPS) per berry. Despite the formation of berries, TPS was absent in 22 crosses using somatic hybrids as a female or male parent which may be due to ovule or embryo abortions. Segregating BC1 generations were evaluated under the same sub-tropical conditions for further exploitation in potato breeding. Based on our study, the somatic hybrids P4, P8 and P10 can be utilized for the introgression of important characters such as high tuber dry matter concontration, resistance to late blight and excellent keeping quality attributes into the cultivated potato via conventional breeding methods for cultivar development in the sub-tropical plains of India.